U.S. patent application number 15/397680 was filed with the patent office on 2018-03-29 for led device and control unit thereof.
The applicant listed for this patent is XIAMEN ECO LIGHTING CO. LTD.. Invention is credited to YANZENG GAO, MINGHAO WU.
Application Number | 20180092178 15/397680 |
Document ID | / |
Family ID | 57997463 |
Filed Date | 2018-03-29 |
United States Patent
Application |
20180092178 |
Kind Code |
A1 |
GAO; YANZENG ; et
al. |
March 29, 2018 |
LED DEVICE AND CONTROL UNIT THEREOF
Abstract
An LED device is disclosed. The LED device comprises a first LED
light string, a second LED light string, a rectifying module, and a
control unit. The control unit generates a driving current flowing
through the first LED light string and the second LED light string.
The control unit cuts off the driving current when the input signal
is between a threshold voltage and a sum voltage.
Inventors: |
GAO; YANZENG; (XIAMEN,
CN) ; WU; MINGHAO; (XIAMEN, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
XIAMEN ECO LIGHTING CO. LTD. |
Xiamen |
|
CN |
|
|
Family ID: |
57997463 |
Appl. No.: |
15/397680 |
Filed: |
January 3, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05B 45/44 20200101;
H05B 45/50 20200101; H05B 45/48 20200101; H05B 45/46 20200101 |
International
Class: |
H05B 33/08 20060101
H05B033/08 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 26, 2016 |
CN |
201610849243.1 |
Claims
1. An LED device, comprising: a first LED light string, the first
LED light string having a first turn-on voltage; a second LED light
string, the second LED light string having a second turn-on
voltage; a rectifying module for receiving an input signal; a
control unit, the control unit being connected to the first LED
light string and the second LED light string, the control unit
being connected to the rectifying module, the control unit
outputting an output current, the output current comprising a
driving current flowing through the first LED light string and the
second LED light string; and wherein the control unit cuts off the
driving current only when the input signal is between a threshold
voltage and a sum voltage, the sum voltage being at least a sum of
the first turn-on voltage and the second turn-on voltage, the
threshold voltage being greater than the first turn-on voltage.
2. The LED device of claim 1, wherein the control unit further
comprises a switch assembly, when a voltage level of the input
signal is higher than a first predetermined voltage level and lower
than a second predetermined voltage level, the switch assembly
connects the first LED light string and the second LED light string
in parallel, and when the voltage level of the input signal is
higher than the second predetermined voltage level, the switch
assembly connects the first LED light string and the second LED
light string in series.
3. The LED device of claim 2, wherein the first predetermined
voltage level is greater than any one of the first turn-on voltage
and the second turn-on voltage.
4. The LED device of claim 2, wherein the second predetermined
voltage level is greater than a sum of the first turn-on voltage
and the second turn-on voltage.
5. The LED device of claim 2, wherein the switch assembly comprises
a first switch, a second switch, and a third switch, when the
voltage level of the input signal is higher than the first
predetermined voltage level and lower than the second predetermined
voltage level, the first switch is connected, the second switch is
connected, and the third switch is disconnected so that the first
LED light string and the second LED light string are connected in
parallel, and when the voltage level of the input signal is higher
than the second predetermined voltage level, the first switch is
disconnected, the second switch is disconnected, and the third
switch is connected so that the first LED light string and the
second LED light string are connected in series.
6. The LED device of claim 1, wherein when the voltage level of the
input signal is lower than any one of the first turn-on voltage and
the second turn-on voltage, no driving current flows through the
first LED light string or the second LED light string.
7. The LED device of claim 1, wherein the control unit further
comprises a regulator module for generating a constant current for
each of the first LED light string and the second LED light
string.
8. The LED device of claim 1, wherein the rectifying module is a
bridge rectifier.
9. The LED device of claim 1, further comprising a resistor
connected between the rectifying module and the control unit.
10. A control unit for an LED driver circuit, the LED driver
circuit driving a plurality of LED strings, the control unit
comprising: a voltage input detection unit, the voltage input
detection unit detecting a voltage level of an input signal and
producing a detection output; a switch assembly, the switch
assembly being connected to the voltage input detection unit, the
switch assembly connecting the LED light strings in parallel when
the voltage input detection unit determines that the voltage level
of the input signal is lower than a predetermined level, the switch
assembly connecting the LED light strings in series when the
voltage input detection unit determines that the voltage level of
the input signal is higher than the predetermined level; and a
regulator module for generating a driving current for the LED light
strings; wherein the driving current is cut off for a time period
only when the switch assembly switches the LED light strings
between a parallel connection and a series connection.
11. The control unit of claim 10, wherein in a rising phase of the
input signal, when the voltage level of the input signal is higher
than a threshold voltage, the control unit cuts off the driving
current.
12. The control unit of claim 10, wherein the switch assembly
further comprises a set of regulator switches for controlling the
regulator module, and the control unit cuts off the driving current
by disconnecting the regulator switches.
13. The control unit of claim 10, wherein the regulator module
further comprises a plurality of regulators for providing the
driving current.
14. The control unit of claim 10, wherein the voltage input
detection unit is a comparator for comparing the voltage level of
the input signal with the predetermined level.
15. The control unit of claim 10, further comprising a logic
circuit for controlling the voltage input detection unit, the
switch assembly, and the regulator module.
16. An LED device, comprising: a set of LED light strings; a
rectifying module for rectifying an input signal; and a control
unit, the control unit being connected to the rectifying module,
the control unit producing a driving current for the set of LED
strings, the control unit cutting off the driving current for a
period of time only when the between a threshold voltage and a sum
voltage, wherein the driving current has a first current value
before the driving current is cut off, the driving current has a
second current value after the driving current resumes from being
cutting off, and the first current value is different from the
second current value.
17. The LED device of claim 16, wherein in a rising phase of the
input signal, when a voltage level of the input signal is higher
than a threshold voltage, the control unit cuts off the driving
current.
18. The LED device of claim 16, wherein in a rising phase of the
input signal, when a voltage level of the input signal is higher
than a sum voltage, the control unit resumes the driving current
from being cut off, the sum voltage being at least two times a
turn-on voltage of any of the LED light strings.
19. The LED device of claim 16, wherein in a falling phase of the
input signal, when a voltage level of the input signal is lower
than a sum voltage, the control unit cuts off the driving current,
the sum voltage being at least two times a turn-on voltage of any
of the LED light strings.
20. The LED device of claim 16, wherein in a falling phase of the
input signal, when a voltage level of input signal is lower than a
threshold voltage, the control unit resumes the driving current
from being cut off.
Description
FIELD OF THE INVENTION
[0001] The invention is related to the field of illumination, in
particular to the field of LED device.
BACKGROUND OF THE INVENTION
[0002] LED light sources has advantages of high luminous
efficiency, low heat generation, electricity saving, and long
lifetime, thus having more and more wide applications. LED lights
will gradually replace conventional illuminative lamps like
incandescent lamps and halogen lamps. With the development of LED
lights, LED lights are driven toward the trend of structural
miniaturization. Common LED light driving circuits in the current
market use an electrolytic capacitor for filtering after
rectifications of voltage inputs, and inductors or transformers are
also needed to be used in circuits.
[0003] Because the large volume of electrolytic capacitors occupy a
larger space of driving circuits, the driving circuits are
difficult to be further miniaturized. Also, the lifetime of
electrolytic capacitors is greatly influenced by ambient
temperature of the space of driving circuits, making electrolytic
capacitors have premature failures, resulting in the shortened
lifetime of the whole light. The larger volume of inductors and
transformers also results in difficulties in miniaturizing driving
structures.
SUMMARY OF THE INVENTION
[0004] One objective of the invention is to provide an LED device
which is more power saving.
[0005] Another objective of the invention is to provide an LED
device which can avoid peak heat generation when an input voltage
level and a driving current are both high.
[0006] According to one aspect of the invention, an LED device is
disclosed. The LED device comprises a first LED light string, a
second LED light string, a rectifying module, and a control
unit.
[0007] The rectifying module receives an input signal. The control
unit is connected to the first LED light string and the second LED
light string. The control unit is connected to the rectifying
module. The control unit outputs an output current. The output
current comprises a driving current flowing through the first LED
light string and the second LED light string.
[0008] The control unit cuts off the driving current when the input
signal is between a threshold voltage and a sum voltage. The sum
voltage is at least a sum of a turn-on voltage of the first LED
light string and a turn-on voltage of the second LED light
string.
[0009] According to another aspect of the invention, a control unit
for an LED driver circuit is disclosed. The driver circuit drives a
plurality of LED strings. The control unit comprises a voltage
input detection unit, a switch assembly, and a regulator
module.
[0010] The voltage input detection unit detects a voltage level of
an input signal and produces a detection output. The switch
assembly is connected to the voltage input detection unit. The
switch assembly connects the LED light strings in parallel when the
voltage input detection unit determines that the voltage level of
the input signal is lower than a predetermined level. The switch
assembly connects the LED light strings in series when the voltage
input detection unit determines that the voltage level of the input
signal is higher than the predetermined level.
[0011] The regulator module generates a driving current for the LED
light strings. The driving current is cut off for a time period
when the switch assembly switches the LED light strings between a
parallel connection and a series connection.
[0012] According to still another aspect of the invention, an LED
device is disclosed. The LED device comprises a set of LED light
strings, a rectifying module, and a control unit.
[0013] The rectifying module rectifies an input signal. The control
unit is connected to the rectifying module. The control unit
produces a driving current for the set of LED strings. The control
unit cuts off the driving current for a period of time. The driving
current has a first current value before the driving current is cut
off. The driving current has a second current value after the
driving current resumes from being cutting off. The first current
value is different from the second current value.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 shows an embodiment of an LED device;
[0015] FIG. 2 shows wave forms of an input signal and an output
current;
[0016] FIG. 3 shows an embodiment of a control unit;
[0017] FIG. 4 shows an embodiment of a regulator module and
corresponding regulator switches;
[0018] FIG. 5 shows three examples of regulators; and
[0019] FIG. 6 shows another three example of regulators.
DETAILED DESCRIPTION OF THE INVENTION
[0020] FIG. 1 shows an embodiment of an LED device. FIG. 2 shows
wave forms of an input signal and an output current. FIG. 3 shows
an embodiment of a control unit. FIG. 4 shows an embodiment of a
regulator module and corresponding regulator switches. FIG. 5 shows
three examples of regulators. FIG. 6 shows another three example of
regulators. According to an embodiment, with reference to FIG. 1
and FIG. 2, an LED device 100 comprises a plurality of LED light
strings 20, a rectifying module 10, and a control unit 30.
[0021] The LED light strings 20 include a first LED light string 21
and a second LED light string 22. In some embodiments, the
rectifying module 10 provides full-wave rectification from an AC
input. A resistor 40 can be placed on a path of the output current
of the control unit 30. The resistor 40 is grounded at one end. The
resistor 40 can also be used to adjust the output current. Although
only two LED light strings are used as an example, more than two
LED light strings can be employed in the LED device 30.
[0022] The first LED light string 21 has a first turn-on voltage.
The second LED light string 22 has a second turn-on voltage. The
rectifying module 10 receives an input signal Uin. The control unit
30 is connected to the first LED light string 21 and the second LED
light string 22. The control unit 30 is connected to the rectifying
module 10. The control unit 30 outputs an output current Iout. The
output current Iout comprises a driving current flowing through the
first LED light string 21 and the second LED light string 22. The
driving current is used to drive the LED light strings 20. The
first light string 21 can comprise a plurality light emitting
diodes. The second light string 22 can comprise a plurality of
light emitting diodes.
[0023] In some embodiments, with reference to FIG. 1 and FIG. 2,
the control unit 30 further comprises a switch assembly 31. When a
voltage level of the input signal Uin is higher than a first
predetermined voltage level U1 but lower than a second
predetermined voltage level U2, the switch assembly 31 connects the
first LED light string 21 and the second LED light string 22 in
parallel. When the voltage level of the input signal Uin is higher
than the second predetermined voltage level U2, the switch assembly
31 connects the first LED light string 21 and the second LED light
string 22 in series.
[0024] In some embodiments, the first predetermined voltage level
U1 is greater than or equal to any one of the first turn-on voltage
and the second turn-on voltage. In some embodiments, the second
predetermined voltage level U2 is greater than or equal to a sum of
the first turn-on voltage of the first LED light string 21 and the
second turn-on voltage of the second LED light string 22.
[0025] In some embodiments, with reference to FIG. 1, the switch
assembly 31 comprises a first switch 311, a second switch 312, and
a third switch 313. When the voltage level of the input signal Uin
is higher than the first predetermined voltage level and lower than
the second predetermined voltage level U2, the first switch 311 is
connected, the second switch 312 is connected, and the third switch
313 is disconnected so that the first LED light string 21 and the
second LED light string 22 are connected in parallel. When the
voltage level of the input signal Uin is higher than the second
predetermined voltage level U2, the first switch 311 is
disconnected, the second switch 312 is disconnected, and the third
switch 313 is connected so that the first LED light string 21 and
the second LED light string 22 are connected in series.
[0026] With reference to FIG. 2, in some embodiments, when the
voltage level of the input signal Uin is lower than any one of the
first turn-on voltage and the second turn-on voltage, no driving
current flows through the first LED light string 21 or the second
LED light string 22. In some embodiments, the first predetermined
voltage level U1 is any one of the first turn-on voltage and the
second turn-on voltage. In some embodiments, the first turn-on
voltage is the same as the second turn-on voltage. In some
embodiments, the first switch 311 and the second switch 312 are
connected and the third switch 313 is disconnected when the input
signal Uin is lower than the first predetermined voltage level
U1.
[0027] When the input signal Uin rises and exceeds the first
predetermined voltage level U1, the first LED light string 21 and
the second LED light string 22 are connected in parallel and a
constant current flows through each of the LED light string. In
some embodiments, the output current Iout is I1, which is the same
as the sum of all constant currents flowing through the LED light
strings.
[0028] In a rising phase of the input signal Uin, when the voltage
level of input signal Uin continues to rise and becomes higher than
a threshold voltage Uth but lower than a sum voltage, the control
unit 30 cuts off the driving current. In some embodiments, the sum
voltage is at least a sum of the first turn-on voltage and the
second turn-on voltage. In some embodiments, the sum voltage is the
second predetermined voltage level U2.
[0029] In some embodiments, the detection of the threshold voltage
Uth can be done by a voltage input detection unit 502 shown in FIG.
3. In some embodiments, the detection of the threshold voltage Uth
can be implemented outside the control unit 30. In some
embodiments, the threshold voltage Uth can be programmed from
outside.
[0030] In the rising phase of the input signal Uin, when the
voltage level of input signal Uin continues to rise and becomes
higher than a sum voltage, the control unit 30 resumes the driving
current from being cut off. The control unit 30 connects the first
LED light string 21 and the second LED light string 22 in series,
and the driving current, which is the output current in this case,
is I2. The sum voltage is at least two times a turn-on voltage of
any of the LED light strings. In some embodiments, the sum voltage
is the second predetermined voltage level U2.
[0031] When the input signal Uin turns into a falling phase and the
voltage level of the input signal Uin is lower than the sum
voltage, the control unit 30 cuts off the driving current. The
control unit 30 connects the first LED light string 21 and the
second LED light string 22 in parallel. The sum voltage is at least
two times a turn-on voltage of any of the LED light strings. In
some embodiments, the sum voltage is the second predetermined
voltage level U2.
[0032] When the voltage level of the input signal Uin keeps falling
and becomes lower than the threshold voltage, the control unit 30
resumes the driving current from being cut off. In this case, the
first LED light string 21 and the second LED light string 22 are
still connected in parallel. When the voltage level of the input
signal Uin continues to fall and becomes lower than the first
predetermined voltage level U1, the driving current is turned
off.
[0033] In some embodiments, the control unit 30 further comprises a
regulator module 504 for generating a constant current for each of
the first LED light string 21 and the second LED light string 22.
In some embodiments, the rectifying module 10 is a bridge
rectifier. In some embodiments, the LED device 100 further
comprises a resistor connected between the rectifying module 10 and
the control unit 30. The regulator module 504 is used to provide
proper driving current for the LED light strings. In most cases,
each LED light string requires a constant current. When the control
unit 30 changes the connection of the LED light strings 20, the
regulator module 504 adjusts the driving current to make sure that
every LED light string has a proper constant current.
[0034] According to another embodiment, with reference to FIG. 1
and FIG. 3, a control unit 30 for an LED driver circuit 100 is
disclosed. The driver circuit 100 drives a plurality of LED
strings. The control unit 30 comprises a voltage input detection
unit 502, a switch assembly 503, and a regulator module 504.
[0035] The voltage input detection unit 502 detects a voltage level
of an input signal Uin and produces a detection output. The switch
assembly 503 is connected to the voltage input detection unit 502.
The switch assembly 503 connects at least a subset of the LED light
strings in parallel when the voltage input detection unit 502
determines that the voltage level of the input signal is lower than
a predetermined level. The switch assembly 503 connects the subset
of the LED light strings in series when the voltage input detection
unit 502 determines that the voltage level of the input signal is
higher than the predetermined level. In some embodiments, the
predetermined level is the voltage level U2.
[0036] The regulator module 504 generates a driving current for the
subset of the LED light strings. The driving current is cut off for
a time period when the switch assembly 503 switches the subset of
LED light strings between a parallel connection and a series
connection. In some embodiments, the regulator module 504 comprises
a plurality of regulators REG 0 604, REG 1 605, and REG 2 606.
Corresponding regulator switches 607, 608, and 609 are connected to
the regulators REG0 604, REG 1 605, and REG 2 606. The regulator
switches 607, 608, and 609 can be controlled to switch on or off
particular regulators in order to provide proper current value for
the LED light strings. The regulator switches 607, 608, and 609 can
all be switched off and as a result all driving currents are cut
off. With reference to FIG. 4, a set of LED light strings are
connected to the regulators REG0 604, REG 1 605, and REG 2 606
through the regulator switches 607, 608, and 609. The set of LED
light strings can be divided into a first subset 601 and a second
subset 602. The first subset can comprise a plurality of unit LED
light strings 603. In this embodiment, all unit LED light strings
603 in the first subset 601 are connected in parallel. The second
subset 602 can comprises a plurality of unit LED light strings
603.
[0037] In the second subset 602, two unit LED light strings 603 are
connected in series, and in turn, the longer LED light strings are
connected in parallel. Any possible parallel and serial connections
can be implemented by a switch assembly as long as proper switches
are provided and are correctly connected. In some embodiments, a
third subset and a fourth subset of the LED light strings 603 can
be implemented with different type of parallel or serial
connections. In some embodiments, the regulator switches 607, 608,
and 609 can be implemented within the switch assembly 504.
[0038] In some embodiments, in a rising phase of the input signal
Uin, when the voltage level of input signal Uin is higher than a
threshold voltage Uth, the control unit 30 cuts off the driving
current. In some embodiments, the switch assembly 503 further
comprises a set of regulator switches 607, 608, and 609 for
controlling the regulator module 504. The control unit 30 cuts off
the driving current by disconnecting the set of regulator switches
607, 608, and 609.
[0039] In some embodiments, the regulator module 504 further
comprises a plurality of regulators 604, 605, and 606 for providing
the driving current. In some embodiments, the voltage input
detection unit 502 is a comparator for comparing the voltage level
of the input signal Uin with the predetermined level. In some
embodiments, the control unit 30 further comprises a logic circuit
505 for controlling the voltage input detection unit 502, the
switch assembly 503, and the regulator module 504.
[0040] According to another embodiment, with reference to FIG. 1
and FIG. 3, an LED device 100 comprises a set of LED light strings
21 and 22, a rectifying module 10, and a control unit 30. The
rectifying module 10 rectifies an input signal Uin.
[0041] The control unit 30 is connected to the rectifying module
10. The control unit 30 produces a driving current for the set of
LED strings 21 and 22. The control unit 30 cuts off the driving
current for a period of time. The driving current has a first
current value before the driving current is cut off. The driving
current has a second current value after the driving current
resumes from being cutting off. The first current value is
different from the second current value. In some embodiments, with
reference to FIG. 2, in the rising phase of the input signal Uin,
the first current value is I1 and the second current value is I2.
In the falling phase of the input signal Uin, the first current
value is I2 and the second current value is I1.
[0042] In some embodiments, in a rising phase of the input signal
Uin, when the voltage level of input signal Uin is higher than a
threshold voltage Uth, the control unit 30 cuts off the driving
current. In some embodiments, in a rising phase of the input signal
Uin, when the voltage level of input signal Uin is higher than a
sum voltage, the control unit 30 resumes the driving current from
being cut off. The sum voltage is at least two times a turn-on
voltage of any of the LED light strings. In some embodiments, the
sum voltage is the second predetermined voltage level U2.
[0043] In some embodiments, in a falling phase of the input signal
Uin, when the voltage level of input signal Uin is lower than a sum
voltage, the control unit 30 cuts off the driving current. The sum
voltage is at least two times a turn-on voltage of any of the LED
light strings. In some embodiments, in a falling phase of the input
signal Uin, when the voltage level of input signal Uin is lower
than a threshold voltage Uth, the control unit 30 resumes the
driving current from being cut off.
[0044] FIG. 5 shows three examples of regulators. FIG. 6 shows
another three examples of regulators. Each of the regulators shown
in FIG. 5 and FIG. 6 can be a design choice to implement a proper
current source. Each regulator has a corresponding I-V curve to
show its characteristics when applying different voltages and
currents.
[0045] Since the LED driver circuit of the invention does not use
electrolytic capacitors, inductors and transformers, but use the
newly designed sectional constant current IC such that the
serial/parallel relations between each LED light string can be
flexibly combined and switched, the space can thus be greatly
reduced. The driving circuit is easily miniaturized and the cost be
reduced.
[0046] Since there is no electrolytic capacitor existing in the
circuit, the hidden trouble of causing the shortened lifetime of
the whole light due to premature failures of electrolytic
capacitors is eliminated. The LED driver circuit can thus be used
in situations with tightened space with higher requirement to the
volume of devices such as MR16 and candle. In addition, the driving
current for the LED light strings is cut off for a specific period,
so that the heat problem caused by high voltage difference in the
integrated circuit can be reduced. The LED device 30 is more power
saving. The LED device 30 can avoid peak heat generation when an
input voltage level and a driving current are both high.
* * * * *